Case 60: water -based batteries

The market

The global battery market will represent nearly $ 74 billion in 2011. The Chinese market is the most important and the one that grows the fastest. The United States, for its part, weighs a turnover of around $ 15 billion for $ 15 billion. The expensive batteries are those who know the strongest growth. The global market of materials for the manufacture of batteries amounts to 3.8 billion dollars annually. The added value generated from the extracted metals to create a finished product is almost one for twenty. The manufacture and sale of batteries is definitely a profitable activity. Although automotive batteries are almost 100 %recycled, it is estimated that 40 billion batteries will end up in the landfills this year. This means that around $ 2 billion in precious and rare metals will be rejected. While the first battery dates back two thousand years, it was Thomas Edison who created the first alkaline battery with a power of 1 to 1.35 V. Today, the electrical power of the batteries is calculated in joules (1 Joule = 1 watt per second). A watt hour (WH) therefore represents 3,600 joules. The global battery market has evolved enormously in recent years. Lead-acid batteries cost $ 0.17 per. These are the cheapest and those that roll the car. Nickel-Cadmium batteries cost almost ten times more ($ 1.50). Lithium ion batteries are the standard used in Nissan electric vehicles at an associated cost of $ 0.47 per. Few people realize that a kilowatt hour of electricity produced by battery can cost 100 to 500 times more than the electricity of the network. The company is ready to pay a high price for mobility. The largest energy storage battery was built by ABB in Fairbanks, Alaska. The huge Nickel-Cadmium battery provides 40 MW, enough electricity for 12,000 people for a maximum of seven minutes. The smallest battery is 2.9 mm by 1.3 mm, the size of a pencil tip and can be loaded for 10 years.

Innovation

A major drawback for batteries is their weight. Light batteries are a priority for industry. The supply of batteries by pumping a rechargeable electrolyte, instead of having to replace or recharge an entire unit, is another innovation that is eminent. The arrival of the vanadium -based battery that can be recharged at least 10,000 times is another breakthrough, even if the media is shortage to meet global demand. However, the batteries are limited in terms of mining, recycling and energy potential. A kilogram of crude oil represents 50 megajoules (MJ) of energy, while a kilogram of lead-acid accumulators can only be used for 0.1 MJ of electricity, 500 times less. This explains why the energy from batteries is so expensive and why the recovery of electricity excess in energy from a storage battery will always be disadvantaged on the competitive level. Weight weight, even the best batteries in the world could theoretically produce only 6 % of the energy offered by oil.

Professor Bo Nordell of the University of Technology of Luleå in Sweden has long been impressed by the capacity of water to store heat. It studied the storage of thermal energy and realized that a cubic meter of water can contain 334 MJ or 93 kWh of heat. The possibility of using ice, storing the energy of frozen winter months or using water heated to solar energy (see case 53), represents a cheap storage mechanism that works Very effectively when applied on a large scale, with a minimum infrastructure cost. There is no limit to the number of recharges. Professor Nordell supported the doctoral thesis of Kjell Skogberg who led to the construction of the first snow cooling installation in the world in Sundsvall, Sweden, for the main hospital in the city, by exploiting the freshness of snow collected during winter.

The first cash flow

Per-Erik Larsson, the project manager designated by the council of the County of Västernorrland, decided to design and operate the energy center. In 2000, the main objective was to avoid dangerous ozone refrigerants, reduce electricity consumption and capture winter snow, mainly collected on roads, roofs and parking lots. When the snow melts, it circulates in the pipes. The design is quite simple: before the water reaches the hospital pipes, it is filtered and crossed by heat exchangers. Heat exchangers have a capacity of 3 MW and transfer the heat of the hospital to melted snow. The hospital water is cooled from 12 to 7 degrees Celsius. The heated cold wearer is then returned to the snow warehouse to melt more snow, which is then pumped towards the heat exchangers and the hospital, in order to continue the cooling. After installing the snow cooling system, the hospital reduced its electricity consumption linked to the cooling of more than 90 %. This long -term solution has a minimum lifespan of 40 years, which means that the system will be recharged 40 times in 40 winter seasons. The inventors then created the company Snowpower AB which today markets this simple battery technique. The Sundsvall experience is a large -scale application of multiple smaller examples that have been developed using water as a means of energy storage. However, most of the systems used heat (instead of the cold) but as the process works on the basis of a temperature differential, it does not matter that the starting point is ice or hot water. Josef Jenni was the pioneer in 1989 with the first solar house, then in 2005 with a solar tank which contains 205 cubic meters of hot water storing the energy which can be converted into electricity. The city of Heerlen, in the Netherlands, was the first to use hot water in the old and closed coal mine wells. Even if the deep mine provides water to 35 degrees Celsius, it is enough - thanks to a series of thermal exchanges - to meet all heating needs in winter and cooling in summer for 350 houses and a shopping center. Water can retain five times more heat than concrete and therefore constitutes an ideal alternative to replace batteries in large -scale operations.

The opportunity

Each house and each city has an elaborate water storage system. When we realize that heating and cooling of air and water heating represents 80% of the energy consumption of a traditional house, the true possibility that is available to us not only to opt For renewable energies, but also for the most efficient energy storage system. The cheapest and abundant environment is water. This allows you to take a fresh look at the need for energy storage, since we can heat (or capture cold water) and store it. The first advantage is that hot water eliminates the risk of bacterial contamination. In Spain, hotels must maintain all the water at 90 degrees Celsius in order to combat the proliferation of E. coli, to then be cooled in a shower or a bath at 38-40 degrees and lose more than 50 % of the on-board energy. If we apply the principle of using what we have ", heated water becomes one of the main sources of electricity. Semiconductor heat exchangers need only a temperature differential of 3 degrees to produce electricity, a phenomenon known as "thermoelectricity". The next time you take a shower, think of the waste -fed energy involved in the mixture of hot and cold water. At the same time, think of the potential if all the already built water tanks could become energy storage tanks, transforming a passive service into an active component requiring a new type of intelligent network. This offers so many opportunities for entrepreneurship that it could well define the "water electrician" profession.